Sulfoaromatic-substituted alkanoic acids and derivatives thereof



United States Patent 3,116,321 SULFOAROMATlC-SUBSTITUTED ALKANOIC ACIDS AND DERIVATIVES THEREOF Christian F. Horn and Harry Vineyard, both of Charleston, W. Va., assignors to Union Carbide Corporation, a corporation of New York No Drawing. Filed Nov. 1, 1961, Ser. No. 149,196 5 Claims. (Cl. 260-470) This invention relates to the production and use of novel compounds, viz., sulfophenox sulfophenylthio-, and sulfophenylsulfonyl-substituted alkanoic acids, their alkali metal sulfonate salts, and the alkyl carboxylate esters thereof.

More particularly, the novel compounds of this invention can be represented by the following generic formula:

wherein X designates a sulfo (SO H) or metallosulfo (--SO M) radical; M designates an alkali metal atom, as for instance, a lithium, sodium, potassium, rubidium, or cesium atom, etc., and preferably designates an alkali metal atom having an atomic number of from 3 to 19, i.e. a lithium, sodium, or potassium atom; Y designates an oxygen or sulfur atom, or a sulfonyl radical; n desig nates an integer having a value of from 1 to about 12, and preferably from 1 to about 8; and R designates an alkyl radical containing from 1 to about 8 carbon atoms, such as a methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl, 2-methylpentyl, Z-ethylbutyl, heptyl, octyl, or Z-ethylhexyl radical, etc., of which the lower alkyl radicals containing from 1 to about 4 carbon atoms are preferred.

Thus, by way of further illustration, the novel compounds of this invention include the sulfophenoxyalkanoic acids, their alkali metal sulfonate salts, and the alkyl carboxylate esters thereof represented by the following subgeneric formula:

I (I) O-(CJ-IMCOOR wherein X, n and R are as defined above. such compounds, there can be mentioned:

As typical of Methyl (4- [potassiumsulfo] phenoxy) acetate Octyl 3-(4-su1fophenoxy)propionate Octyl 3- 4- [sodiumsulfo] phenoxy propionate 2-ethy1hexyl 4-(4-sulfophenoxy)butyrate 2-ethylhexyl 4- (4- [lithiumsulfo] phenoxy) butyrate Butyl 5-(2-sulfophenoxy)pentanoate Butyl 5- 2- [potassiumsulfo] phenoxy) pentanoate Propyl 6-(3-sulfophenoxy)hexanoate Propyl 6- 3- [sodiumsulfo] phenoxy hexanoate Ethyl 2-ethyl-6-(4-sulfophenoxy)hexanoate Ethyl 2-ethyl-6- (4- [lithiumsulfo] phenoxy) hexanoate Methyl 8-(4-sulfophenoxy) octanoate Methyl 8- (4- [potassiumsulfo] phenoxy) octanoate Methyl 12-(4-sulfophenoxy)dodecanoate Methyl 12-(4-[sodiumsulfo]phenoxy)dodecanoate, and the like.

The novel compounds of this invention also include the sulfophenylthioalkanoic acids, their alkali metal sulfonate salts, and the alkyl carboxylate esters thereof represented by the following sub-generic formula:

(III) S(CnH2n) 000R wherein X, n, and R are as defined above. As typical of such compounds there can be mentioned:

(2-sulfophenylthio)acetic acid (2- [sodiumsulfo] phenylthio) acetic acid 3-sulfophenylthio acetic acid (3- [lithiumsulfo] phenylthio) acetic acid (4-sulfophenylthio) acetic acid (4- [potassiumsulfo] phenylthio) acetic acid 3-(4-sulfophenylthio)propionic acid 3-(4-[sodiumsulfo1phenylthio)propionic acid 4-(4-sulfophenylthio)butyric acid 4- (4- [lithiumsulfo1phenylthio butyric acid 5-(Z-sulfophenylthio)pentanoic acid 5- (2- [potassiumsulfo] phenylthio) pentanoic acid 6-(3-sulfophenylthio)hexanoic acid 6-(3-[sodiumsulfo]phenylthio)hexanoic acid 2-ethyl6- (4-sulfophenylthio hexanoic acid 2-ethyl-6-(4-[lithiumsu1fo]phenylthio)hexanoic acid 8-(4-sulfophenylthio)octanoic acid 8- (4- [potassiumsulfo] phenylthio) octanoic acid 12-(4-sulfophenylthio)dodecanoic acid 12- (4- [sodiumsulfo] phenylthio) dodecanoic acid Methyl (2-sulfophenylthio)acetate Methyl (2- [sodiumsulfo] phenylthio) acetate Methyl 3 sulfophenylthio acetate Methyl (3- [lithiumsulfo] phenylthio) acetate Methyl (4-sulfophenylthio)acetate Methyl (4- [potassiumsulfo] phenylthio) acetate Octyl 3-(4-sulfophenylthio)propionate Octyl 3- 4- [sodiumsulfo] phenylthio propionate 2-ethylhexy1 4-(4-sulfophenylthio)butyrate 2-ethylhexyl 4- (4- [lithiumsulfo] phenylthio butyrate Butyl 5-(2-sulfophenylthio)pentanoate Butyl 5-(2-[potassiumsulfo]phenylthio)pentanoate Propyl 6-(3-sulfophenylthio)hexanoate Propyl 6- 3- [sodiumsulfo] phenylthio hexanoate Ethyl 2-ethyl-6-(4-sulfophenylthio)hexanoate Ethyl 2-ethyl-6- (4- [lithiumsulfo] phenylthio) hexanoate Methyl 8-(4-sulfophenylthio)octanoate Methyl 8- (4- [potassiumsulfo] phenylthio octanoate Methyl 12-(4-sulfophenylthio)dodecanoate Methyl 12-(4- [sodiumsulfo] phenylthio) dodecanoate,

and the like.

The novel compounds of this invention further include SOz-(Cflin) COOR wherein X, n and R are as defined above. As typical of such compounds, there can be mentioned:

( 2-sulfophenylsulfonyl acetic acid (2- [sodiumsulfo] phenylsulfonyl) acetic acid (3-sulfophenylsulfonyl)acetic acid (3- [lithiumsulfo] phenylsulfonyl) acetic acid (4-sulfophenylsulfonyl)acetic acid (4- [potasiumsulfo] phenylsulfonyl acetic acid 3-(4-sulfophenylsulfonyl)propionic acid 3- (4- [sodiumsulfo]phenylsulfonyl propionic acid 4-(4-sulfophenylsulfonyl)butyric acid 4-(4- [lithiumsulfo] phenylsulfonyl butyric acid 5-(2-sulfophenylsulfonyl)pentanoic acid 5-(2-[potassiumsulfo]phenylsulfonyDpentanoic acid 6-(3-sulfophenylsulfonyl)hexanoic acid 6- 3- [sodiumsulfo] phenylsulfonyl hexanoic acid 2-ethyl-6-(4-sulfophenylsulfonyl)hexanoic acid 2-ethyl-6-(4-[lithiumsulfo]phenylsuIfonyDheXanoic acid 8-(4-sulfophenylsulfonyl)octanoic acid 8- (4- [potassiumsulfo] phenylsulfonyl) octanoic acid 12-(4-sulfophenylsulfonyl)dodecanoic acid 12-(4- [sodiumsulfo] phenylsulfonyl) dodecanoic acid Methyl (2-sulfophenylsulfonyl)acetate Methyl (2- [sodiumsulfo] phenylsulfonyl acetate Methyl (3-sulfophenylsulfonyl)acetate Methyl (3- [lithiumsulfo] phenylsulfonyl) acetate Methyl (4-sulfophenylsulfonyl)acetate Methyl (4- [potassiumsulfo] phenylsulfonyl) acetate Octyl 3-(4-sulfophenylsulfonyl)propionate Octyl 3- (4- [sodiumsulfo] phenylsulfonyl propionate 2-ethylhexyl 4-(4-sulfophenylsulfonyl)butyrate Z-ethylhexyl 4- (4- [lithiumsulfo] phenylsulfonyl) butyrate Butyl 5-(2-sulfophenylsulfonyl)pentanoate Butyl 5- (2- [potassiumsulfo] phenylsulfonyl pentanoate Propyl 6- 3-sulfophenylsulfonyl) hexanoate Propyl 6-( 3- [sodiumsulfo] phenylsulfonyl) hexanoate Ethyl 2-ethyl- 6-(4-sulfophenylsulfonyl)hexanoate Ethyl 2-ethy1-6-(4-[lithiumsulfo]pl1enylsulfonyl)hexanoate Methyl 8-(4-sulfophenylsulfonyl)octanoate Methyl 8-(4-[potassiumsulfo]phenylsulfonyl)octanoate Methyl 12-(4-sulfophenylsulfonyl)dodecanoate Methyl 12-(4- [sodiumsulfo] phenylsulfonyl) dodecanoate, and the like.

O-(OnHZn) COOR wherein n and R are as defined above. As typical of such known compounds there can be mentioned:

Phenoxyacetic acid 3-phenoxypropionic acid 4-phenoxybutyric acid 5-phenoxypentanoic acid 6-phenoxyhexanoic acid 2-ethy1-6-phenoxyhexanoic acid 8-phenoxyoctanoic acid 12-phenoxydodecanoic acid 4 Methyl phenoxyacetate Octyl 3-phenoxypropionate 2-ethylhexyl 4-phenoxybutyrate Butyl 5-phenoxypentanoate Propyl 6-phenoxyhexanoate Ethyl 2-ethyl-d-phenoxyhexanoate Methyl 8-phenoxyoctanoate Methyl 12-phenoxydodecanoate, and the like.

The phenoxyalkanoic acids and esters hereinabove described can themselves be obtained, for example, by the reaction of an alkali metal phenolate with a haloalkanoic acid or ester, in accordance with the following equation:

wherein M designates an alkali metal atom, such as a sodium atom, etc., X designates a halogen atom, such as a chlorine atom, etc., and n and R are as defined above. Such a reaction can be carried out by bringing the phenolate and the haloalkanoic acid or ester into reactive admixture in an aqueous medium at a temperature of from about 30 C. to about 100 C., or higher, or when an ester reactant is employed, in an alcoholic medium, under reflux.

The conversion of the phenoxyalka-moic acid or ester represented above by Formula V, to the corresponding sulfonic acid derivative represented above by Formula II, wherein X designates the sulzfo radical, can be carried out by known sulfonation procedures. Thus, :for example, the phenoxyalkanoic acid or ester can he sulfionated by reaction with a mild sulfonating agent comprised of a mixture of acid and acetic 'anhydride, at a temperature of drum about -15 C. to about 50 C., and preferably trom about 0 C. to about 25 C. The phenoxyallk'anioic acid or ester, of which the latter is preferably employed, is best intnoduced to the sulfonating agent in solution, using, by Way of illustration, an inert solvent such as methylene dichloride, ethylene dichloride, ethyl acetate, or the like. The mole ratio of sulfuric acid to acetic anhydride in the sulfonatin-g agent can vary firom about 0.1 to about 1 mole of sulfuric acid per mole of acetic anhydride, with a ratio of from about 0.2 to about 0.6 mole of sulfuric acid per mole of acetic anhydride being preficrred. The mole ratio of sulfuric acid to the phenoxyalkanoic acid or ester can vary from about 0.5 to about 5 moles of sulfuric acid per mole of the phenoxyalkianoic acid or ester, with a ratio from about 0.8 to about 1.5 moles of sulfuric acid per mole of the phenloxyalkanoic acid or ester being preferred.

Produced as hereirlebove described, the sulfonated pherioxyalkanoic acid or ester product can be recovered, if desired, in any convenient manner, such as by crystalllization. and filtration, by isolation as a residue product upon evaporation or distillation or any solvent present, etc. Moreover, while the para-substituted deriwative in which the sulfo radical is located at the 4-position of the phenyl ring is most readily produced, other sulfonated derivatives, i.e., the orthoor metaasubstituted derivatives, are also often formed, or can be obtained by varying the sulfionattion reaction in a manner determinable by those skilled in the art in light of this disclosure.

When the starting material employed is the free acid, i.e., when R of Formula V is hydrogen, the sulfonated product is readily converted to the corresponding alkyl carboxylate ester by esterification in conventional manner with an alkyl alcohol containing from 1 to about 8, and preferably from 1 to about 4 carbon atoms. The presence of the sulfo radical during the esterification serves to catalyze the reaction (auto-catalysis), thus obviating the conventional addition of an esterification catalyst.

The sulfon-ated phenoxyalkanoic acid or ester can thereafter be reacted with an alkali metal hydroxide or alkoxide, or an alkali metal salt of an acid Weaker than sullionic acid, such acetic acid or benzoic acid, etc, to form the corresponding alkali metal salt, i.e., met-allosul-fo derivative. Preferably, such a reaction is carried out in an alcoholic or aqueous solution, and at a temperature of from about 5 C. to about 110 C., and preferably from about 20 C. to about 80 C.

The mole ratio of allcali metal hydroxide, alkoxide, or salt to the sulfophenoxyalkanoic acid or ester can vary about 1 to about 5 moles of the alkali metal-containing compound per mole of the sulionated phenoxyalkanoic acid or ester, with a ratio of from about 1 to about 3 moles of the alkali metal-containing compound per mole of the sulfophenoxyalkanroic acid or ester being preferred. Moreover, when the sulfonated product undergoing reaction is the alkanoate ester, the conversion of the product to the alkali metal sulfonate derivative can be effected conveniently by titration with an alkali metal hydroxide or alkoxide, preferably in alcoholic solution, to pH of 7 to 8.

The alkali metal sulfonate salt thus produced can subsequently be recovered in any convenient manner, such as those described above in connection with the recovery of the sulfonic acid derivatives.

By way of further example, the sulfophenylthioalkanoic acids and derivatives thereof, as contemplated by this invention, can be obtained by otherwise identical process steps, i.e., sulfonation, esteru'fication, salt forma tion, etc, to those described above in connection with the production of the sul'fiophenoxyalkano-ic acids and derivatives, except for the nature of the starting materials. More particularly, the thio compounds can be obtained by substituting for the phenoxyalkanoic acid or ester reactant represented above by Formula V, a member of another known class of compounds, viz., the phenylthioalhancic acids and alkyl esters thereof represented by the formula:

(VII) -so..In,.) o 0R wherein n and R are as defined above. As typical or such known compounds, there can be mentioned:

Phenylthioacetic acid 3-phenylthiopropionic acid 4-phenylthiobutyric acid S-phenylthiopentanoic acid 6-phenylthiohexanoic acid 2-ethyl-6-phenylthiol1exanoic acid 8-phenylthiooctanoic acid IZ- henylthiododecanoic acid Methyl phenylthioacet-ate Octyl 3-phenylthiopropionate Z-ethylhexyl 4-phenylthiob-utyrate Butyl S-phenylthiopentanoate Propyl -phenylthiohexanoate Ethyl 2-ethyl-6-phenylthiohexanoate Methyl 8-phenylthiooctanoate Methyl IZ-phenylthiododecanoate, and the like.

The phenylthioalkanoic acids and esters hereinabove described can be obtained, for example, by the reaction of an alkali metal thiophenolate with an haloalkanoic acid or ester in accordance with the following equation:

(VIII) SM+X(CnH2n) C O O R s (o nH2.) o 0 0 R-l-MX' wherein M, X, n and R are as defined above. Such a reaction can be carried out as otherwise described above in connection with the production of phenoxyialkanoic acids and esters (Equation VI).

Moreover, when the sulfophenylsulfonylalkanoic acids and derivatives thereof, as contemplated by this invention, are the desired products, such compounds can be obtained as hereinabove described in connection with the production of the sulfophenylthioalkanoic acids and derivatives with an additional process step, ziv., the oxidation of the phenylthioalkanoic acid or ester. The oxidation is preferably conducted immediately subsequent to sulfonation and any esterification, but could be carried out prior to such process steps, although less conveniently.

The oxidation can be performed by reacting the sulfonated or unsulfonated phenylthioalkanoic acid or ester with a conventional oxidizing agent, such as peracetic acid, hydrogen peroxide, etc., preferably in a suitable solvent such as dimethylformamide, acetone, ethyl acetate, etc. The reaction temperature can vary from about 30 C. to about 100 C., and preferably is in the range of from about 20 C. to about C., using a mole ratio of oxidizing agent to the phenylthioalkanoic acid or derivative of from about 2 to about 5, and preferably from about 2 to about 3.

The novel compounds of this invention find. use in a wide variety of application. Such compounds can be used, for instance, as intermediates in the production of dyestuffs, pharmaceuticals, and ion exchange resins. In addition, the novel compounds of this invention are eminently suited for use as modifiers in the production of high melting, crystalline, linear polyesters, especially polyesters formed by the polycondensation reaction of terephthalic acid, or ester-forming derivative thereof, with an aliphatic diol, or ester-forming derivative thereof. The modified polyesters prepared in part from the compounds of this invention, and particularly from the alkali metal sulfonate derivatives of this invention, i.e., by the incorporation of the novel compounds of this invention in otherwise conventional polycondensation reaction mixtures, can, in turn, be employed to produce fibers which are readily dyeable with cationic and disperse dyestuffs by standard dyeing procedures. The dyed fibers thus obtained possess shades having good wash fastness and light fastness, as wellas stability to conventional dry cleaning procedures. The modified polyesters prepared in part from the compounds of this invention can also be used to produce films and molded articles.

That the novel compounds of this invention could be employed in the production of high-melting, crystalline, linear polyesters was surprising and unexpected since pheuoxy-, phenylthio-, and phenylsulfonylalkanoic acids and esters, the basic structures of the compounds of this invention, ordinarily discolor and/or decompose when heated to the temperatures employed in making the polyesters. Thus, it was unexpected that the compounds of this invention would be sufficiently stable, both chemically and thermally, to withstand the polycondensation conditions in the presence of the other reactants, as Well as the high temperatures necessary for spinning the polyesters. It was also surprising that the fibers produced from these polyesters showed no disadvantages in physical properties over the unmodified polyester fibers, and that they exhibit greatly enhanced dyeability properties, as well as many other desirable textile properties. The improved dyeability of the modified polyesters is believed due in no small part to the flexibility or rotatability of the sulfophenyl (or metallosulfophenyl) radical of the compounds of this invention about the adjacent oxygen or sulfur atom, thereby making the sulfo (or metallosulfo) radial more accessible to the dye molecules during dyeing operations.

At the same time, the novel compounds of this invention, being monofunctional ester-forming compounds, or derivatives thereof, advantageously serve as chainterminators in the polycondensation reaction producing the polyesters, thereby affording effective control over the molecular weight of the polyester products. The compounds of this invention, are, in fact, particularly well suited for use as molecular weight regulators in a con tinuous polycondensation process due to their extremely low volatility. Thus, the compounds are not readily removed from the reaction melt by either vacuum or contact with inert gas which may be passed through the melt during the polycondensation. Moreover, since the compounds of this invention occur in the resulting polyesters only at the end of linear chains, do not materially effect the desirable physical properties of the polyesters. Hence, the proportion in which the compounds of this invention are employed or incorporated in order to produce polyesters having improved dyeability, i.e., from about 1 to about 5 mole percent based upon the total carboxylate content of the polyesters, is ordinarily much less than that in which difunctional dye-assistants, which interrupt the polymer chain, are conventionally employed.

The following specific examples serve as further illustration of the present invention.

Example I To a 5-liter, round bottomed, 3-necked flask equipped with a stirrer, thermometer, and a dropping funnel, there were charged 764 grams of acetic anhydride. The anhydride was cooled to a temperature of 5 C., whereupon 374 grams of 98 percent sulfuric acid were added dropwise thereto, accompanied by stirring and continued cooling, so that the temperature of the resulting mixture was maintained in the range of from -5 C. to C. To this mixture there were slowly added -a solution containing 518 grams of phenoxyacetic acid dissolved in 1500 milliliters of ethyl acetate. The addition was effected over a period of 10 minutes, accompanied by continued stirring and cooling, so that the temperature of the resulting mixture was maintained in the range of from C. to 0 C. The reaction mixture was then heated at a temperature in the range of from 35 C. to 40 C. for a period of two hours and allowed to stand overnight at room temperature. -In this manner, a solution of (4- sulfophenoxy)acetic acid was obtained. The solution was then stripped of ethyl acetate under reduced pressure, up to a kettle temperature of 65 C. 1500 milliliters of methanol were subsequently added to the residue, and the resulting mixture was refluxed for a period of 4 hours to esterify the acid present. In this manner, a solution of methyl (4-sulfophenoxy)acetate was obtained. Approximately three-fourths of the solution undergoing reflux was thereafter cooled to about room tempearture, diluted with 1 liter of methanol, and neutralized, i.e., titrated to a pH of about 7, with a percent methanolic sodium hydroxide solution. A precipitate was formed, and isopropyl ether was added to the reaction product to further the precipitation. The precipitate was then collected and washed with acetonitrile on a Buchner funnel. In this manner, 447 grams of a crude methyl (4-[sodiumsulfo] phenoxy)acetate product were obtained. Upon purification by recrystallization from glacial acetic acid and treatment with activated carbon, a substantially pure, white,

crystalline methyl (4- [sodiumsulfo] phenoxy) acetate product was obtained having a melting point above 300 C.

Such -a product was subsequently employed as a modi tier in the production of fiber-forming polyesters as follows. A mixture of 194 grams of dimethyl terephthalate, 4.1 grams of methyl (4-[sodiumsulfo]phenoxy)acetate, 180 grams of ethylene glycol, 0.02 gram of antimony oxide, and 0.09 gram of zinc acetate were charged to a reactor and heated at a temperature of 188 C. for a period of 4.25 hours to bring about an ester exchange, while distilling the methanol formed during the course of reaction. Thereafter, the reaction mixture was: heated at a temperature in the range of from 188 C. to 220 C. for a period of 1.25 hours to remove the glycol ex cess. The temperature was subsequently maintained in the range of from 269 C. to 275 C. for a period of 4.75 hours to carry out the polycondensation. During this period, a vigorous stream of nitrogen was passed through the melt at atmospheric pressure. The crystalline polymer thus obtained had a melting point of 258 260 C., and was characterized by excellent dyeable fiber-forming and cold drawing properties. In like manner, butyl (4-[potassiumsulfo]phenoxy)acetate, produced by the sulfonati'on of phenoxyacetic acid, followed by esterification with butanol, and then titration with potassium hydroxide, is also employed to produce modified, dyeable fiber-forming polyethylene te-rephtlralate polyesters.

In addition, a solution containing 50 grams of the methyl (4-[sodiumsulfo]phenoxy) acetate, dissolved in 250 milliliters of water, was refluxed for a period of 8 hours. Thereafter, upon evaporation of the water present, 30 grams of (4-[sodiumsulfo1phenoxy)acetic acid was recovered as a residue product. Analysis. Calculated for C H O Na: C, 36.50; H, 2.68. Found: C, 36.91; H, 2.88. Infrared analysis was consistent therewith.

Example II To a 500 milliliter, 4-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel, there were charged 96 grams of acetic anhydride. The anhydride was cooled to a temperature of 0 C., whereupon 51 grams of sulfuric acid were added dropwise thereto, accompanied by stirring and continued cooling, so that the temperature of the resulting mixture was main tained at about 0 C. To this mixture there were slowly added a solution containing 98 grams of 6-phenoxyhexanoic acid dissolved in milliliters of ethylene dichloride. The addition was effeoted over a period of 4 hours, accompanied by continued stirring and cooling, so that the temperature of the resulting mixture was maintained in the range of from 0 C. to 10 C. The reaction mixture was then heated at -a temperature of 40 C. for a period of 3.5 hours, and subsequently cooled to a temperature of 25 C., after which, 150 milliliters of methanol were added to the product. The solution was transferred to an evaporating dish and left standing overnight to permit the solvent to evaporate. In this manner, 'a residue containing 6-(4-sulfophenoxy)- hexanoic acid was obtained. The residue was subsequently dissolved in 300 milliliters of methanol, and the resulting solution was refluxed for a period of 6.5 hours to esterify the acid present, which included the acetic anhydride component of the sulfonating agent. In this manner, a solution of methyl 6-(4-sulfophenoxy)hexano-ate was obtained. This solution was distilled to remove the methyl acetate formed during esterification and any trace of ethylene dichloride present. During the distillation, methanol was added to the solution to maintain a constant volume of about 400 milliliters. Thereafter, the solution was cooled to about room temperature and titrated with a methanolic sodium hydroxide solution to a pH of 7.1. A precipitate was formed, and was filtered and purified by recrystallization, twice from acetic acid and once from methanol. In this manner, 79 grams of substantially pure methyl 6-(4-[sodiumisulfo]phen oxy)hexanoate were obtained. Analysis-Calculated for C H O Na: C, 48.14; H, 5.28. Found: C, 47.91; H, 5.72. Infrared analysis was consistent therewith.

When employed as a modifier for a polyethylene terephthalate polyester in a manner similar to that described in Example I, the incorporation of methyl 6-(4-[sodiumsulfo]phenoxy)-hexanoate resulted in the production of a crystalline polymer characterized by excellent dyeable fiber-forming and cold drawing properties. In similar manner, ethyl 8-(4-[lithiumsulfo]phenoxy)-octanoate, produced by the sulfonation of ethyl 8-phenoxyoctanoate, followed by titration with lithium hydroxide, is also employed to produce modified dyeable fiber-forming polyethylene terephthalate polyesters.

Example III A solution of sodium thiophenolate was produced by the reaction of 1 mole of thiophenol with 1 mole of sodium hydroxide in 400 milliliters of methanol at a temperature of 30 C. The sodium thiophenolate solution was then added dropwise to 150 milliliters of a methanol solution containing 1 mole of methyl 6-chlorohexanoate, while refluxing the resulting mixture at a temperature of 64 C. 'Refluxing was continued for a period of 4 hours after the addition was completed, and was attended by the formation of sodium chloride as a precipitate. The solution was filtered to remove the sodium chloride precipitate and distilled on a steam bath to remove the methanol present. The residue was dissolved in isopropyl ether and filtered to remove any trace of sodium chloride present. The solution was then evaporated to remove the isopropyl ether present and distilled at a temperature of 152 C. under a reduced pressure of less than 1 millimeter of mercury. In this manner, 235 grams of methyl 6-phenylthiohexanoate was obtained as a yellowish distillate.

To a 500 milliliter, 4-necked flask equipped with a stirrer, condenser, thermometer, and dropping funnel, there were charged 61 grams of acetic anhydride. The anhydride was cooled to C., whereupon 29 grams of sulfuric acid were added dropwise thereto, accompanied by stirring and continued cooling, so that the temperature of the resulting mixture was maintained at about 0 C. To this mixture there were slowly added 65 grams of methyl G-phenylth-iohexanoate obtained as described above. The addition was effected over a period of about 25 minutes, and was accompanied and followed by continued stirring and cooling, so that the temperature of the resulting mixture was maintained in the range of from 0 C. to 10 C. for a period or" 4 hours. The reaction mixture was then slowly warmed to room temperature over a period of 3 hours. In this manner, a solution of methyl 6-(4-sulfophenylthio)hexanoate was obtained. To this solution there were added 250 millilitiers of methanol, and the resulting solution was refluxed fora period of 3 hours to esterify the acid present, i.e., the acetic anhydride component of the sulfonating agent. The solution was then distilled to remove the methyl acetate formed by the esterification. During the distillation, methanol was added to the solution to maintain a constant volume of about 400 milliliters. Thereafter, the solution was cooled to about room temperature and titrated with a methanolic sodium hydroxide solution to a pH of 7.0. A precipitate was formed and was filtered and purified by recrystallization from acetic acid and from methanol. In this manner, 33 grams of substantially pure methyl 6-(4-[sodiumsulfo]pl1enylthio)- hexanoate were obtained. Analysis.Caloulated for C13H17O5S2N21I C, 45.87; H, 5.03. Found: C, 45.34; H, 4.78. Infrared analysis was consistent therewith.

When employed as a modifier for a polyethylene terephthalate polyester in a manner similar to that described in Example I, the incorporation of methyl 6-(4- [sodiumsulfo]phenylthio)hexanoate resulted in the production of a crystalline polymer characterized by excellent dyeable fiber-forming and cold drawing properties. In similar manner, methyl 8-(4-[potassiumsulfo1phenylthio)octanoate, produced by the sulfonation of 8-phenylthioocatnoic acid, followed by esterification with methanol, and then titration with potassium hydroxide, is also employed to produce modified, dyeable fiber-forming polyethylene terephthalate polyesters.

Example IV A solution of sodium thiophenolate was produced by the reaction of 3 moles of thiophenol with 3 moles of sodium hydroxide in 1 liter of absolute ethanol at a temperature of 27 C. for a period of 20 minutes. The sodium thiophenolate solution was then added dropwise to 1.5 liters of absolute ethanol containing 3 moles of ethyl chloroacetate, while refluxing the resulting mixture at a temperature of C. Refluxing was continued for a period of 6 hours after the addition was completed, and was accompanied by the formation of sodium chloride as a precipitate. The solution was filtered to remove the sodium chloride precipitate and distilled to remove the ethanol present. The residue was dissolved in hexane and filtered to remove any trace of sodium chloride present. The solution was then distilled at a temperature of C. to 97 C. under a reduced pressure of l millimeter of mercury. In this manner, 533 grams of ethyl phenylthioacetate was obtained as a water-clear distillate having a refractive index of 1.5421 at 27 C. Analysis-Calculated for C H O S: C, 61.19; H, 6.17; S, 16.34. Found: C, 61.25; H, 6.38; S, 16.29. Infrared and mass spectrometric analyses were consistent therewith.

To a 2-liter, 4-necked flask equipped with a stirrer, condenser, thermometer, and dropping funnel, there was charged 286 grams of acetic anhydride. The anhydride was cooled to a temperature of --10 C., whereupon 131 grams of sulfuric acid were added dropwise thereto, accompanied by stirring and continued cooling, so that the temperature of theresulting mixture was maintained in the range of from 10 C. to 0 C. To this mixture there were slowly added 250 grams of ethyl phenylthioacetate. The addition was effected over a period of about 20 minutes, and was accompanied and followed by continued stirring and cooling so that the temperature of the mixture was maintained in the range of from 0 C. to 5 C. for a period of 4 hours. The reaction mixture was then slowly warmed to room temperature over a period of 0.5 hour. In this manner, a solution of ethyl (4- sulfophenylthio)acetate was obtained. To this solution there was added 1 liter of absolute ethanol, and the re sulting solution was refluxed for a period of 3 hours to esterify the acid present, i.e., the acetic anhydride component of the sulfonating agent. The solution was then distilled to remove the ethyl acetate formed by the esterification. During the distillation, ethanol was added to the solution to maintain a constant volume of about 2 liters. Thereafter, 750 grams of the solution were cooled to about room temperature and titrated with an ethanolic potassium hydroxide solution to a pH of 7.8. A precipitate was formed and was filtered and purified by extraction with methanol in a Soxhlet extractor. In this manner, 275 grams of substantially pure ethyl (4- [potassiumsulfo]phenylthio)acetate were obtained. Analysis.-Calculated for C H O S K: S, 20.39. Found: S, 19.97. Infrared analysis was consistent therewith.

When employed as a modifier for a polyethylene terephthalate polyester in a manner similar to that described in Example I, the incorporation of ethyl (4-[potassiumsulfo]phenylthio)acetate resulted in the production of a crystalline polymer characterized by excellent dyeable fiber-forming and cold drawing properties. In like manner, butyl(4- [lithiumsulfo]phenylthio)acetate, produced by the sulfonation of butyl phenylthioacetate, followed by titration with lithium hydroxide, is also employed to 1 I produce modified, dyeable fiber-forming polyethylene terephthalate polyesters.

In addition, 150 grams of an ethanolic (4-sulfophenylthio)acetate solution obtained as described above in this example, was evaporated to yield (4-sulfophenylthio)acetate as a residue product. The structure of this product was confirmed by infrared analysis. 44 grams of the product was then admixed with 300 milliliters or distilled Water, and the resulting solution was refluxed for a period of 16 hours. Thereafter, upon evaporation of the Water, 42 grams of (4-sul fophenylthio)acetic acid were recovered as a residue product. Infrared analysis again confirmed the structure of the product.

Example V In the manner described in Example IV, 250 grams of ethyl phenylthioacetate was sulfonated to produce ethyl (4-sulfophenylthio)acetate by reaction with a sulfonating agent consisting of 131 grams of sulfuric acid in 286 grams of acetic anhydride. Upon completion of the sulfonation, the resulting solution was added dropwise to 1 liter of ethanol maintained at a temperature in the range of from C. to 10 C., and stirred therewith over a period of 30 minutes. The thio compound was then oxidized to the corresponding ethyl(4-sulfophenylsulfonyl)acetate by the addition to the solution of 1041 grams of a 22.35 percent solution of peracetic acid in ethyl acetate (a 20 percent excess of peracetic acid). The oxidation was carried out by stirring the mixture of reactants at a temperature [maintained in the range of from 0 C. to 25 C. for a period of 20.5 hours. Upon completion of the oxidation, the solution was refluxed for a period of 3 hours to esterify the acetic acid present. The solution was then distilled to remove the ethyl acetate formed by the esterification. During the distillation, ethanol was added to the solution to maintain a constant volume of about 3 liters. In this manner, an ethanol solution of ethyl(4-sulfophenylsulfonyl)acetate was obtained. Thereafter, the solution was cooled to about room temperature and 1100 grams of the solution was titrated with an ethanolic solution of potassium hydroxide to a pH of 7.8. A precipitate was formed and was filtered and purified by extraction with methanol in a Soxhlet extractor. In this manner, 285 grams of substantially pure ethy1(4-[potassiumsulfo]phenylsulfonyl) acetate was obtained. Analysis. Calculated for C H O S K: S, 18.51. Found: S, 18.05. Infrared analysis was consistent therewith.

When employed as a modifier for a polyethylene terephthatlate polyester in a manner similar to that described in Example I, the incorporation of ethyl (4-[potassiumsulfo] phenylsulfonyDacetate resulted in the production of a crystalline polymer characterized by excellent dy'eable fiber-forming and cold drawing properties. In like manner, methyl (4-[lithiumsulfo]phenylsuifonyl)octanoate, produced by the sulfonation of methyl 8-(phenylthio)octanoate, followed by oxidation with peracetic acid, and then titration with lithium hydroxide, is also employed to produce modified, dyeable fiber-forming polyethylene terep'hthalate polyesters.

In addition, 300 grams of an ethanolic (4-sulfopheny l sul fonyl)acetate solution obtained as described above in this example was evaporated to yield (4-sulfophenylsulfonyl)acetate as a residue product. The structure of this product was confirmed by infrared analysis. 61 grams of the product was then admixed with 300 milliliters of distilled water, and the resulting solution was refluxed for a period of 16 hours. Thereafter, upon evaporation of the water, 52 grams of (4-sulfophenylsulfonyl)acetic acid were recovered as a residue product. Infrared analysis again confirmed the structure of the product.

Example VI In the manner, described above in Example III, 119 grams of methyl 6-phenylthiohexanoate were sulfonated to produce methyl 6-(4-sulfophenylthio)hexanoate by reaction with a sulfonating agent consisting of 54 grams of sulfuric acid in 112 grams of acetic anhydride. Upon completion of the sulfonation, the resulting solution was 5 added dropwise to 250 milliliters of methanol maintained at a temperature in the range of from 0 C. to C., and stirred therewith, over a period of 30 minutes. The thio compound was then oxidized to the corresponding methyrl 6-(4-sulfophenylsulfonyl)hexanoate by the addition to the solution of 350 grams of a 26 percent solution of peracetic acid in ethyl acetate (a percent excess of peracetic acid). The oxidation was carried out by stirring the mixture of reactants at a temperature maintained in the range of from 0 C. to C. for a period of 20 hours. Upon completion of the oxidation, the solution was refluxed for a period of 4 hours to esterify the acid present. The solution was then distilled to remove the methyl acetate formed by the esterification. During the distillation, methanol was added to the solution to maintain a constant volume of 400 milliliters. In this manner, a methanol solution of methyl (4-sulfophenylsulfonyl) hexanoate was obtained. Thereafter, the solution was cooled to about room temperature and titrated with a methanolic sodium hydroxide solution to a pH of 7.0. A precipitate was formed and was filtered and purified by recrystallization from methanol. In this manner, 43 grams of substantially pure methyl 6-(4-[sodiumsulfo] phenylsulfonyl)hexanoate, having a melting point of 317- 9 C. were obtained. Analysis.Calculated for C H O S Na C, 41.93; H, 4.60. Found: C, 41.93; H, 4.66. Infrared analysis was consistent therewith.

When employed as a modifier for a polyethylene tereph thalate polyester in a manner similar to that described in Example I, the incorporation of methyl 6-(4-[sodiurnsulfo]phenylsulfonyl)hexanoate resulted in the production of a crystalline polymer characterized by excellent dyeable fiber-forming and cold drawing properties. In like manner, butyl 6-(4-[potassiumsulfo]phenylsulfonyl) hexanoate, produced by the sulfonation of 6-phenylthiohexanoic acid, followed by oxidation with peracetic acid, then by esterification with butanol, and finally by titration with potassium hydroxide, is also employed to produce modified, dyeable fiber-forming polyethylene terephthalate polyesters.

What is claimed is:

1. A compound of the formula:

wherein M is an alkali metal atom having an atomic References Cited in the file of this patent UNITED STATES PATENTS Kranzlein May 5, 1942 Baldridge Oct. 24, 1961 OTHER REFERENCES Conant: The Chemistry of Organic Compounds (New York, 1943), page 264. r Lowy et al.: An Introduction to Organic Chemistry (New York, 1945), pages 213-215. 

1. A COMPOUND OF THE FORMULA: 